La pupila cambia con la luz.

with

Breakdown of La pupila cambia con la luz.

• la luz: the light
• cambiar: to change
• la pupila: the pupil (eye)

Questions & Answers about La pupila cambia con la luz.

Why is it la pupila and not el pupilo?

Because pupila is a feminine noun in Spanish.

In this sentence, la pupila means the pupil (of the eye).

A useful warning: pupila can also mean female pupil/student in other contexts, but here the context is clearly about the eye because of cambia con la luz.

• la pupila = the pupil of the eye
• el pupilo = a male pupil/ward, in other contexts

So the article la matches the noun pupila.

What form is cambia?

Cambia is the third-person singular present indicative of cambiar.

So it means:

• it changes
• sometimes, depending on context, it is changing

Here, the subject is la pupila, which is singular, so cambia must also be singular:

• la pupila cambia = the pupil changes

Other forms for comparison:

• yo cambio = I change
• tú cambias = you change
• él/ella cambia = he/she/it changes
• las pupilas cambian = the pupils change

Why does Spanish use the singular here instead of ?